<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>伸缩容器_项目在主轴的基准长度</title>
    <style>
        body{
            display: flex;
        }
        .outer{
            width: 1000px;
            height: 1000px;
            background-color: gray;
            /*开启弹性盒子*/
            display:flex;
            /*主轴方向*/
            flex-direction: column;
            /*主轴换行方式*/
            flex-wrap: wrap;
            /*主轴对齐方式*/
            justify-content: flex-start;
           /*侧轴单行对齐*/
            align-items: baseline;
        }
        .inner{
            width: 200px;
            height: 200px;
            border: 1px solid black;
            box-sizing: border-box;
            background-color: skyblue;
        }
        .inner2{
            /*
            设置伸缩项目在主轴上的基准长度,若主轴是横向的宽失效,若主轴是纵向的高失效
            使用这个属性,会覆盖掉伸缩项目的宽/高
            */
            flex-basis: 300px;
        }

    </style>
</head>
<body>
<div class="outer">
    <div class="inner">1</div>
    <div class="inner inner2">2</div>
    <div class="inner">3</div>

</div>
</body>
</html>